Triethylamine Functionalized Elastomer in Barrier Applications

ABSTRACT

A halogenated elastomer partially functionalized with triethylamine, in a mixture with fiiier and a cure package, suitable for use as an air barrier in an innertube or tire innerliner, is disclosed. The halogenated elastomer can be a polymer comprising C 4  to C 7  isoolefm derived units, para-alkylstyrene derived units, para-(haloalkylstyrene) derived units, and para-(triethylammoniumalkylstyrene) derived units. The Mooney viscosity of the elastomer can be controlled by the degree of triethylamine functionalization. Also disclosed is a method for making an article using the tri ethy iamine-functionalized elastomer.

FIELD OF THE INVENTION

This invention relates to low-permeability elastomers useful in airbarrier applications, and particularly to compositions, methods andarticles based on triethylamine-functionalized isobutylene polymers.

BACKGROUND OF THE INVENTION

Rubbery copolymers containing a majority of isobutylene units are wellknown for their low gas permeability, unique damping properties, and lowsurface energy that make them particularly desired in applications suchas inner tubes and tire innerliners. For better compatibility orco-curability with other elastomer components in the applications, anunsaturated comonomer and/or a comonomer containing reactivefunctionality has been used Among the isobutylene polymers, theisobutylene/para-methylstyrene copolymers (IPMS) are of particularinterest. The para-methylstyrene (PMS) derived units in the polymers canbe partially brominated to give an isobutylene/PMS/BrPMS terpolymer(BIMS). The BIMS can be further functionalized via the reactive benzylicbromine for conversion to a variety of functionalized isobutylenepolymers, as described in U.S. Pat. No. 5,162,445. Another advantage ofIPMS copolymers and BIMS terpolymers is their excellent resistance toozone and aging due to the completely saturated backbones.

The tire industry has a desire to enhance the barrier property ofelastomers used in inner tubes and innerliners. For example, elastomernanocomposites have been developed. Nanocomposites are polymer systemscontaining inorganic particles with at least one dimension in thenanometer range. Some examples of these are disclosed in U.S. Pat. No.6,060,549, U.S. Pat. No. 6,103,817, U.S. Pat. No. 6,034,164, U.S. Pat.No. 5,973,053, U.S. Pat. No. 5,936,023, U.S. Pat. No. 5,883,173, U.S.Pat. No. 5,807,629, U.S. Pat. No. 5,665,183, U.S. Pat. No. 5,576,373,and U.S. Pat. No. 5,576,372. Common types of inorganic particles used innanocomposites are phyllosilicates, an inorganic substance from thegeneral class of so called “nanoclays.” Ideally, intercalation shouldtake place in the nanocomposite, wherein the polymer inserts into thespace or gallery between the clay surfaces. Ultimately, it is desirableto have exfoliation, wherein the polymer is fully dispersed with theindividual nanometer-size clay platelets.

Unfortunately the incompatibility between the hydrophobic isobutyleneelastomer and hydrophilic inorganic clays has made it very difficult toachieve a good clay dispersion or exfoliation in the elastomer. Oneapproach has been the use of organically modified montmorillonite clays.Organoclays are typically produced through ion-exchange reactions thatreplace sodium ions that exist on the surface of sodium montmorillonitewith organic molecules, such as alkyl or aryl ammonium compounds knownin the industry as swelling or exfoliating agents. See, e.g., U.S. Pat.No. 5,807,629, WO 02/100935, and WO 02/100936. Other backgroundreferences include U.S. Pat. No. 3,516,959, U.S. Pat. No. 3,898,253,U.S. Pat. No. 5,333,662, U.S. Pat. No. 5,576,373, U.S. Pat. No.5,633,321, U.S. Pat. No. 5,665,183, U.S. Pat. No. 5,807,629, U.S. Pat.No. 5,936,023, U.S. Pat. No. 6,036,765, U.S. Pat. No. 6,121,361, U.S.Pat. No. 6,552,108, WO 94/22680, WO 01/85831, and WO 04/058874.

Functionalization of the BIMS polymers for use in nanocomposites hasalso been shown to provide a better interaction between thefunctionality on the polymer and clay surface, which can lead to ahigher degree of clay dispersion and exfoliation. This, in turn, canprovide the nanocomposite with an even better barrier property. Thepreferred functionalities for permeability improvements in BIMS polymershave been ammonium (—NR), hydroxyl (—OH), ester (—OOR), and ether (—OR).

Unfortunately, when ammonium functionality is incorporated into apolymer and/or a nanocomposite with clay, the viscosity of the polymercan increase significantly due to the ionomeric associations of thefunctional groups in the polymer backbone. A low viscosity is needed tofacilitate processing of the elastomer in conventional rubbercompounding and tire building equipment. One way to try to attain a lowviscosity has been to include a higher alkyl tail in the functionalgroup, which can inhibit the ionomeric interactions. For example,published applications US 2005/0027057, US 2005/0027058 and US2005/0032937 disclose treatment of BIMS polymers with tertiary aminespreferably having a long chain alkyl substituent.

The tire industry has a continuing need for elastomers andnanocomposites that can be used in air barrier applications, having bothan improved barrier property and a controllable processability.

SUMMARY OF THE INVENTION

We discovered that partial triethylamine (TEA) functionalization ofhalogenated elastomers such as BIMS polymers can offer severaladvantages in elastomer and especially nanocomposite applications overother functional polymers. While the TEA-functionalized BIMS promotesdispersion of the nanoclay and improves the barrier property, the Mooneyviscosity of triethylamine-functional polymer, and thus itsprocessability, can be readily adjusted by controlling the amount offunctionality in the polymer.

Typically, when ammonium functionality had been incorporated into apolymer, the viscosity of the polymer would increase significantly dueto the ionomeric associations of the functional groups in the polymerbackbone. Surprisingly, the presence of three ethyl groups in thepartially functionalized polymer provides shielding of the ionicinteractions between the functional groups to prevent a severe rise inviscosity. The three ethyl groups in the TEA-functional polymer providejust the right amount of shielding of the ionic interactions between thefunctional groups to prevent a severe rise in viscosity. Thus, the useof TEA can give the functional polymer not only enough functionality tointeract with clay for a good barrier property, but, more importantly,also leave it with good processability that is desired in rubbercompounding and tire manufacturing.

In one embodiment, the present invention can provide a vulcanizablerubber composition, comprising an elastomer, a tiller, and a curepackage. The elastomer can comprise C₄ to C₇ isoolefin derived unitspara-alkylstyrene derived units, para-(haloalkylstyrene) derived unitsand para-(triethylammoniumalkylstyrene) derived units having thetriethylammoniumalkyl group pendant to the elastomer E according to thefollowing formula:

wherein R and R¹ are the same or different and are one of hydrogen, C₁to C₇ alkyls, and primary and secondary C₁ to C₇ alkyl halides,preferably hydrogen. In an embodiment, the elastomer can comprisehalogenated poly(isobutylene-co-p-methylstyrene) wherein a portion ofthe benzylic halogen groups are triethylamine-functionalized.

In embodiments, the elastomer can comprise a molar ratio oftriethylamine functionality to benzylic halogen from 1:100 to 1:1, orfrom 1:20 to 1:2. From 1 to 60 mole percent of the alkylstyrene groupscan be halogenated or triethylamine-functionalized. The elastomer cancomprise in various embodiments from 0.5 to 20 weight percentmethylstyrene, from 0.1 to 3 mole percent halomethylstyrene, and/or from0.05 to 1 mole percent triethylammoniumalkylstyrene. In an embodiment,the para-(triethylammoniumalkylstyrene) derived units can be present atfrom 0.01 to 0.5 percent by weight of the elastomer. In anotherembodiment, the elastomer can further comprise multiolefin derivedunits, halogenated multiolefin derived units, or the like, or acombination thereof. In another embodiment, the elastomer can have aMooney viscosity (ML 1+8, 125° C.) from 30 to 120.

In an embodiment, the vulcanizable rubber composition can also include asecondary rubber selected from the group consisting of natural rubber,polybutadiene rubber, nitrile rubber, silicon rubber, polyisoprenerubber, poly(styrene-co-butadiene) rubber, poly(isoprene-co-butadiene)rubber, styrene-isoprene-butadiene rubber, ethylene-propylene rubber,brominated butyl rubber, chlorinated butyl rubber, halogenated isoprene,halogenated isobutylene copolymers, polychloroprene, star-branchedpolyisobutylene rubber, star-branched brominated butyl rubber,poly(isobutylene-co-isoprene) rubber,poly(isobutylene-co-p-methylstyrene), halogenatedpoly(isobutylene-co-p-methylstyrene), and the like, including mixturesthereof.

In embodiments, the filler can be selected from carbon black, modifiedcarbon black, silica, precipitated silica, clay, nanoclay and the like,including mixtures thereof. In one embodiment, the filler comprisesnanoclay, which can be exfoliated. The exfoliating agent can be selectedfrom the group consisting of ammonium ion, alkylamines, alkylammoniumion (primary, secondary, tertiary and quaternary), phosphonium orsulfonium derivatives of aliphatic, aromatic and arylaliphatic amines,phosphines, sulfides and the like, and including mixtures thereof. In anembodiment, the composition can include from 1 to 100 phr of thenanoclay.

In one embodiment, the curing agents can comprise zinc, zinc stearate,fatty acids, sulfur, or the like, or a mixture thereof

In another aspect, the invention can provide an air barrier structuresuch as an inner tube or tire innerliner. In an embodiment, thevulcanizable rubber composition described above can be formed into theair barrier structure, and can be cured in the form of the air barrierstructure.

A further aspect of the invention can provide a method of preparing anelastomeric article. The method can include the steps of: meltprocessing a mixture of the partially ionomerized, partially halogenatedelastomer, the filler and the cure package described above; forming themelt processed mixture into a green article, and curing the formedarticle. In one embodiment, the article can be an inner tube, and inanother embodiment, a tire innerliner formed from the elastomer mixture.

In one embodiment, the method can include adjusting an overall contentof the para-(triethylammoniumalkylstyrene) in the elastomer to control aviscosity of the mixture in the melt processing step.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 graphically illustrates the controllability of viscosity of ahalogenated isoolefin copolymer (BIMS) partially functionalized withtriethylamine in varying proportions according to embodiments of thepresent invention, in comparison with the same copolymer functionalizedwith dimethylethanolamine showing a much stronger dependence of Mooneyviscosity on the level of functionality which makes the polymer verydifficult to process.

FIG. 2 compares the X-ray diffraction spectra of a nanocomposite ofbrominated isobutylene-p-methylstyrene copolymer (BIMS) and atriethylamine-functionalized BIMS polymer (TEA-BIMS), showing theenhanced d-spacing, i.e. a larger spacing between clay sheets andindicating a higher degree of intercalation and/or exfoliation in theTEA-BIMS nanocomposite. FIG. 3 is a transmission electron microscopy(TEM) image of the TEA SIMS nanocomposite of FIG. 2 showing a highdegree of clay exfoliation according to an embodiment of the invention.

FIG. 4 is a TEM image of the BIMS nanocomposite of FIG. 2 for acomparison and showing large tactoids of unseparated clay sheets.

DETAILED DESCRIPTION OF THE INVENTION

This invention describes vulcanizable and cured compositions of atriethylamine-functionalized elastomer, articles made from thecompositions, and methods of making the articles using the compositions.The triethylamine functionalization can provide an improved barrierproperty (less permeable) and at the same time can provide improvedprocessability through a mechanism for controlling the viscosity of theelastomer and the composition.

As used herein, “polymer” may be used to refer to homopolymers,copolymers, interpolymers, terpolymers, etc. Likewise, a copolymer mayrefer to a polymer comprising at least two monomers, optionally withother monomers.

As used herein, when a polymer is referred to as comprising a monomer,the monomer is present in the polymer in the polymerized form of themonomer or in the derivative form the monomer. Likewise, when afunctionalized polymer is described with reference to the component usedto functionalize the polymer or a particular derivative form, it isunderstood that functionalizing component is present in the form of thefunctional group actually derived from that component. For example, theproduct of functionalization of brominatedpoly(isobutylene-co-p-methylstyrene) (BIMS) with triethylamine may bereferred to as triethylamine functionalized BIMS, triethylammonium-BIMS(TEA-BIMS) or a similar expression, it being understood that the pendantfunctional group may comprise triethylammonium ion, triethylammoniumsalt, or another derivative.

As used herein, “elastomer” or “elastomeric composition” refers to anypolymer or composition of polymers (such as blends of polymers)consistent with the ASTM D1566 definition. Elastomer includes mixedblends of polymers such as melt mixing and/or reactor blends ofpolymers. The terms may be used interchangeably with the term “rubber.”

As used herein, “phr” is ‘parts per hundred rubber’ and is a measurecommon in the art wherein components of a composition are measuredrelative to a major elastomer component, based upon 100 parts by weightof the elastomer(s) or rubber(s).

As used herein, “isobutylene based elastomer” or “isobutylene basedpolymer” refers to elastomers or polymers comprising at least 70 molepercent repeat units from isobutylene.

As used herein, isoolefin refers to any olefin monomer having at leastone carbon having two substitutions on that carbon.

As used herein, “multiolefin” refers to any monomer having two or moredouble bonds, for example, a multiolefin may be any monomer comprisingtwo conjugated double bonds such as a conjugated diene such as isoprene.

As used herein, “nanocomposite” or “nanocomposite composition” refers topolymer systems containing inorganic particles with at least onedimension in the nanometer range within a polymer matrix.

As used herein, “intercalation” refers to the state of a composition inwhich a polymer is present between each layer of a platelet filler. Asis recognized in the industry and by academia, some indicia ofintercalation can be the shifting and/or weakening of detection of X-raylines as compared to that of original platelet fillers, indicating alarger spacing between vermiculite layers than in the original mineral,

As used herein, “exfoliation” refers to the separation of individuallayers of the original inorganic particle, so that polymer can surroundor surrounds each particle. In an embodiment, sufficient polymer ispresent between each platelet such that the platelets are randomlyspaced. For example, some indication of exfoliation or intercalation maybe a plot showing no X-ray lines or larger d-spacing because of therandom spacing or increased separation of layered platelets. However, asrecognized in the industry and by academia, other indicia may be usefulto indicate the results of exfoliation such as permeability testing,electron microscopy, atomic force microscopy, etc.

As used herein the Mooney viscosity is determined in accordance withASTM D-1646, ML 1+8 at 125° C., unless otherwise specified.

In an embodiment, the nanocomposite can include at least onetriethylamine-functionalized halogenated elastomer comprising C₄ to C₇isoolefin derived units. The isoolefin may be a C₄ to C₇ compound, inone embodiment selected from isobutylene, isobutene, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-2-butene, 4-methyl-1-pentene and the like.The elastomer may also include other monomer derived units.

In one embodiment, the halogenated elastomer includes at least onestyrenic monomer, which may be any substituted styrene monomer unit, anddesirably can be selected from para-alkylstyrenes, wherein the alkyl canbe selected from any C₄ to C₅ alkyl or branched chain alkyl. In adesirable embodiment, the styrenic monomer can be p-methylstyrene (PMS).

In another embodiment, the elastomer can include at least onemultiolefin, which may be a C₄ to C₁₄ diene, conjugated or not, in oneembodiment selected from isoprene, butadiene,2,3-dimethyl-1,3-butadiene, myrcene, 6,6-dimethyl-fulvene, hexadiene,cyclopentadiene, methylcyclopentadiene, piperylene and the like.

The halogenated elastomers in one embodiment of the invention can berandom elastomeric copolymers of a C₄ to C₇ isoolefin, such asisobutylene and a para-alkylstyrene comonomer, preferablyp-methylstyrene containing at least 80%, more preferably at least 90% byweight of the para-isomer, and can also include functionalizedinterpolymers wherein at least some of the alkyl substituents groupspresent in the styrene monomer units can contain benzylic halogen ortriethylammonium, for example, from functionalization with triethylaminevia the benzylic halogen. Preferred materials may be characterized asinterpolymers containing the following monomer units randomly spacedalong the polymer chain:

wherein R¹⁰ and R¹¹ are independently hydrogen, lower alkyl, preferablyC₁ to C₇ alkyl, and primary or secondary alkyl halides; and X is afunctional group such as halogen or triethylammonium. Preferably R¹⁰ andR¹¹ are hydrogen. Up to 60 mole percent of the para-substituted styrenepresent in the interpolymer structure may be the functionalizedstructure (5) above in one embodiment, and in another embodiment from0.1 to 5 mole percent. In yet another embodiment, the amount offunctionalized structure (5) is from 0.4 to 1 mole percent.

The functional group X may be a combination of a halogen and atriethylammonium functional group which may be incorporated bynucleophilic substitution of benzylic halogen with triethylamine. Mostuseful of such functionalized materials are elastomeric randominterpolymers of isobutylene and para-rnethylstyrene containing from 0.5to 20 mole percent para-methylstyrene, wherein up to 60 mole percent ofthe methyl substituent groups present on the benzyl ring contain amixture of halogen, e.g. a chlorine or preferably a bromine atom(para-(bromomethylstyrene)), and triethylammonium, and may optionallycomprise other functional groups such as ester and ether. Thehalogenated elastomers are commercially available as EXXPRO™ Elastomers(ExxonMobil Chemical Company, Houston Tex.), and abbreviated as “BIMS”The BIMS can be treated with substoichiometric triethylamine to obtainthe partially functionalized triethylamine-BIMS, abbreviated herein asTEA-BIMS.

These functionalized interpolymers can have a substantially homogeneouscompositional distribution such that at least 95% by weight of thepolymer has a para-alkylstyrene content within 10% of the averagepara-alkylstyrene content of the polymer. Desirable interpolymers canalso be characterized by a narrow molecular weight distribution (Mw/Mn)of less than 5, more preferably less than 2.5, a preferred viscosityaverage molecular weight in the range of from 200,000 up to 2,000,000,and a preferred number average molecular weight in the range of from25,000 to 750,000 as determined by gel permeation chromatography.

The TEA-BIMS polymers may be prepared by a slurry polymerization of themonomer mixture using a Lewis acid catalyst, followed by halogenation,preferably bromination, in solution in the presence of halogen and aradical initiator such as heat and/or light and/or a chemical initiator,and followed by electrophilic substitution of bromine with a differentfunctional moiety such as triethylammonium.

Preferred TEA-BIMS polymers generally contain from 0.1 to 5 mole percentof functionalized-methylstyrene groups relative to the total amount ofmonomer derived units in the polymer. In another embodiment, the totalamount of bromomethyl and TEA-methyl groups can be from 0.2 to 3.0 molepercent, from 0.3 to 2.8 mole percent in yet another embodiment, from0.4 to 2.5 mole percent in yet another embodiment, and from 0.3 to 2.0in yet another embodiment, wherein a desirable range may be anycombination of any upper limit with any lower limit. Expressed anotherway, preferred copolymers can contain from 0.2 to 10 weight percent oftotal bromine and TEA, based on the weight of the polymer, from 0.4 to 7weight percent total bromine and TEA in another embodiment, and from 0.6to 6 weight percent in another embodiment, and can be substantially freeof ring halogen or halogen in the polymer backbone chain.

In various embodiments, the molar ratio of TEA-methyl to bromomethyl inthe TEA-BIMS polymer can range from a lower limit of 1100, 1:50, 1:20,or 1:10, to an upper limit of 1:1, 1:2, 1:3, or 1:4, wherein a desirablerange may be any combination of any upper limit with any lower limit.The proportion of TEA should be sufficient to improve the barrierproperty, which usually requires a minimum level of TEA functionalitybut does not necessarily improve the barrier property at higherproportions of TEA above the minimum or threshold level Above thethreshold TEA functionality level, the Mooney viscosity can increasewith additional TEA functionality, for example, the Mooney increase canbe substantially linear in proportion to the level of TEA functionality.At excessive TEA functionality levels, the Mooney may become too high tocompound and process the elastomer, or may require excessive levels ofprocessing aids used to lower the viscosity such as oils, resins, or thelike. In one embodiment, the conversion of benzylic bromine to ammoniumfunctionality can be used as a design space variable to target thedesired Mooney viscosity of the elastomer and/or a vulcanizablecomposition prepared using it.

In one embodiment of the invention, the interpolymer is a copolymer ofC₄ to C₇ isoolefin derived units (or isomonoolefin), para-methylstyrenederived units (PMS), para-(bromomethylstyrene) derived units (BrPMS),and para-(triethylammoniummethylstyrene) derived units (TEAPMS), whereinthe TEAPMS units are present in the interpolymer from 0.1 to 1.0 molepercent based on the total moles of isoolefin and PMS, BrPMS units arepresent in the interpolymer from 0.3 to 3.0 mole percent based on thetotal moles of isoolefin and PMS, and the PMS derived units are presentfrom 3 to 15 weight percent based on the total weight of the polymer inone embodiment, and from 4 weight percent to 10 weight percent inanother embodiment.

Optionally, the TEA-BIMS polymer can also be functionalized with anamine in addition to the triethylamine. The other aminefunctionalization can be at a proportion or degree that the advantagesof the viscosity characteristics or the barrier property of the TEA aresubstantially realized. In embodiments, the other amine functionalizedmonomer units can comprise a lower limit from 0.001, 0.01 or 0.1 up toan upper limit of 5, 2.1 or 0.5 mole percent, based on the total molesof TEA-functionalized monomer units, wherein a range can be from anylower limit to any upper limit. One embodiment is a nanocompositecomprising a clay and a halogenated elastomer comprising C₄ to C₇isoolefin derived units; wherein a first portion of the halogen in theelastomer is electrophilically substituted with TEA and a second portionwith an amine functionalized group other than TEA such that thehalogenated elastomer also comprises an amine-functionalized monomerunit described by the following group pendant to the elastomer E:

wherein R and R¹ are the same or different and are one of hydrogen, C₁to C₇ alkyls, and primary and secondary alkyl halides; and wherein R²,R³ and R⁴ are the same or different and are selected from the groupconsisting of hydrogen, substituted or unsubstituted C₁ to C₂₀ alkenyls,substituted or unsubstituted C₁ to C₂₀ aryls, C₁ to C₂₀ aliphaticalcohols, C₁ to C₂₀ aliphatic ethers, C₁ to C₂₀ carboxylic acids,nitriles, polyethoxyls, acrylates, and esters, with the proviso that R²,R³ and R⁴ are not all ethyl.

The acrylate can be described by the following formula:

wherein R⁵, R⁶ and R⁷ are the same or different and are selected fromhydrogen, C₁ to C₇ alkyl and C₁ to C₇ alkenyl. The polyethoxyls can beobtained in one embodiment by functionalization via the benzylic brominein the BIMS with ethoxylated amines (or the corresponding ammonium ion)having the following structure:

wherein R⁸ is a C₁ to C₂₀ alkyl; and wherein x+y is from 2 to 50, e.g.,2, 5, 10, 15, or 50.

The acrylates can be obtained in one embodiment by functionalization viathe benzylic bromine in the 131MS with a member selected fromdimethylaminoethylacrylate, dimethylaminomethylacrylate,N-methylamino-bis-2-propanol, N-ethylamino-bis-2-propanol,dimethylaminoethylmethacrylate, diethylaminopropanol,diethylethanolamine, dimethylamino-1-propanol, tripropanolamine,triethanolamine, aminolauric acid, betaine, and combinations thereof.

A secondary rubber or “general purpose rubber” component may be presentin compositions and end use articles of the present invention. Theserubbers can include, but are not limited to, natural rubbers,polyisoprene rubber, poly(styrene-co-butadiene) rubber (SBR),polybutadiene rubber (BR), poly(isoprene-co-butadiene) rubber (IBR),styrene-isoprene-butadiene rubber (STBR), ethylene-propylene rubber(EPM), ethylene-propylene-diene rubber (EPDM), polysulfide, nitrilerubber, propylene oxide polymers, star-branched butyl rubber andhalogenated star-branched butyl rubber, brominated butyl rubber,chlorinated butyl rubber, star-branched polyisobutylene rubber,star-branched brominated butyl(polyisobutylene/isoprene copolymer)rubber; poly(isobutylene-co-p-methylstyrene) and halogenatedpoly(isobutylene-co-p-methylstyrene), such as, for example, terpolymersof isobutylene derived units, p-methylstyrene derived units, andp-bromomethylstyrene derived units, and mixtures thereof.

A desirable embodiment of the secondary rubber component can includenatural rubber. Natural rubbers are described in detail by Subramaniamin RUBBER TECHNOLOGY 179-208 (Maurice Morton, Chapman & Hall 1995).Desirable embodiments of the natural rubbers can be selected fromMalaysian rubber such as SMR CV, SMR 5, SMR 10, SMR 20, and SMR 50 andmixtures thereof, wherein the natural rubbers have a Mooney viscosity at100° C. (ML 1+4) of from 30 to 120, more preferably from 40 to 65.

Polybutadiene rubber (BR) is another desirable secondary rubber usefulin the composition of the invention. The Mooney viscosity of thepolybutadiene rubber as measured at 100° C. (ML 1+4) may range from 35to 70, from 40 to about 65 in another embodiment, and from 45 to 60 inyet another embodiment. Some commercial examples of these syntheticrubbers useful in the present invention are NATSYN, BUDENE 1207 or BR1207 (Goodyear Chemical Company). A desirable rubber is highcis-polybutadiene (cis-BR). By “cis-polybutadiene” or “highcis-polybutadiene,” it is meant that 1,4-cis-polybutadiene is used,wherein the amount of cis component is at least 95%. An example of ahigh cis-polybutadiene commercial product used in the composition isBUDENE 1207 cis-BR.

Rubbers of ethylene and propylene derived units such as EPM and EPDM arealso suitable as secondary rubbers. Examples of suitable comonomers inmaking EPDM are ethylidene norbornene, vinyl norbornene, 1,4-hexadiene,dicyclopentadiene, as well as others. These rubbers are described inRUBBER TECHNOLOGY 260-283 (1995). A suitable ethylene-propylene rubberis commercially available as VISTALON™ (ExxonMobil Chemical Company,Houston Tex.).

In another embodiment, the secondary rubber can be a halogenated butylrubber. The halogenated butyl rubber can be brominated butyl rubber, andin another embodiment can be chlorinated butyl rubber. Generalproperties and processing of halogenated butyl rubbers are described inRUBBER TECHNOLOGY 311-321 (1995). Butyl rubbers, halogenated butylrubbers, and star-branched butyl rubbers are described by Edward Kresgeand H. C. Wang in 8 KIRK-OTHMER ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY934-955 (John Wiley & Sons, Inc. 4th ed. 1993).

The secondary rubber component can include, but is not limited to atleast one or more of brominated butyl rubber, chlorinated butyl rubber,star-branched polyisobutylene rubber, star-branched brominated butyl(polyisobutylene/isoprene copolymer) rubber; halogenatedpoly(isobutylene-co-p-methylstyrene), such as, for example. terpolymersof isobutylene derived units, p-methylstyrene derived units, andp-bromomethylstyrene derived units (BIMS), and the like halomethylatedaromatic interpolymers as in U.S. Pat. No. 5,162,445; U.S. Pat. No.4,074,035; and U.S. Pat. No. 4,395,506; halogenated isoprene andhalogenated isobutylene copolymers, polychloroprene, and the like, andmixtures of any of the above. Some embodiments of the halogenated rubbercomponent are also described in U.S. Pat. No. 4,703,091 and U.S. Pat.No. 4,632,963.

In one embodiment of the invention, a so called semi-crystallinecopolymer (“SCC”) can be present as the secondary “rubber” component.Semi-crystalline copolymers are described in WO00/69966. Generally, theSCC is a copolymer of ethylene or propylene derived units and α-olefinderived units, the α-olefin having from 4 to 16 carbon atoms in oneembodiment, and in another embodiment the SCC is a copolymer of ethylenederived units and α-olefin derived units, the α-olefin having from 4 to10 carbon atoms, wherein the SCC has some degree of crystallinity. In afurther embodiment, the SCC is a copolymer of 1-butene derived units andanother α-olefin derived unit, the other a-olefin having from 5 to 16carbon atoms, wherein the SCC also has some degree of crystallinity. TheSCC can also be a copolymer of ethylene and styrene.

The secondary rubber component of the elastomer composition may bepresent in a range up to 90 phr in one embodiment, up to 50 phr inanother embodiment, up to 40 phr in another embodiment, and up to 30 phrin yet another embodiment. In yet another embodiment, the secondaryrubber is present from at least 2 phr, from at least 5 phr in anotherembodiment, and from at least 10 phr in yet another embodiment. Adesirable embodiment may include any combination of any upper phr limitand any lower phr limit.

The composition of the invention may also include one or more fillercomponents such as calcium carbonate, clay, nanoclay, mica, silica andsilicates, talc, titanium dioxide, and carbon black.

In one embodiment, the composition can include swellable inorganic clayto form nanocomposites. Swellable layered inorganic clay materials caninclude natural or synthetic phyllosilicates, particularly smectic clayssuch as montmorillonite, nontronite, beidellite, volkonsleoite,laponite, hectorite, saponite, sauconite, magadite, kenyaite, stevensiteand the like, as well as vermiculite, halloysite, aluminate oxides,hydrotalcite and the like. These layered clays generally compriseparticles containing a plurality of silicate platelets having athickness of 8-12 Å tightly bound together at interlayer spacings of 4 Åor less, and contain exchangeable cations such as Na⁺, Ca⁺², K⁺ or Mg⁺²present at the interlayer surfaces.

The layered clay can be exfoliated by suspending the clay in a watersolution. Preferably, the concentration of clay in water is sufficientlylow to minimize the interaction between clay particles and to fullyexfoliate the clay. In one embodiment, the aqueous slurry of clay canhave a clay concentration of between 0.1 and 5.0 weight percent; between0.1 and 3.0 weight percent in other embodiments. Organoclays can beobtained by using an organic exfoliating agent such as, for example,tertiary amines, diamines, polyamines, amine salts, as well asquaternary ammonium compounds. Organoclays are available commerciallyunder the trade designation CLOISITE, for example.

The amount of clay or exfoliated clay incorporated in the nanocompositesin accordance with this invention is sufficient to develop animprovement in the mechanical properties or barrier properties of thenanocomposite for example, tensile strength or oxygen permeability.Amounts of clay in the nanocomposite generally range from 0.5 to 10weight percent in one embodiment, and from 1 to 5 weight percent inanother embodiment, based on the polymer content of the nanocomposite.Expressed in parts per hundred rubber, the clay or exfoliated clay maybe present from 1 to 30 phr in one embodiment, from 2 to 20 phr inanother embodiment, and from 3 to 10 phr in another embodiment.

The TEA-BIMS-nanoclay nanocomposites can generally be prepared using avariety of processes, such as solution blending, melt blending, or anemulsion process. For example, PCT Application Ser. No. PCT/US/22714discloses melt blending procedures; published application US2007-0015853 discloses a method for preparing clay-butyl rubbernanocomposites from an emulsion of rubber solution and aqueous claydispersion; and U.S. application Ser. No. 11/183,361 for Split-StreamProcess for Making Nanocomposites by W. Weng et al., filed Jul. 18,2005, discloses a method for preparing clay-butyl rubber nanocompositesby preparing a concentrated nanocomposite from a slipstream of therubber and blending the concentrate with a main rubber stream.

As used herein, fillers can include inorganic particles forming part ofthe nanocomposite matrix, e.g. clay particles having a dimension in thenanometer range, and larger clay particles can also be used as anadditional filler in the nanocomposites, if desired.

In one embodiment, the filler can include carbon black or modifiedcarbon black. The preferred filler is semi-reinforcing grade carbonblack present at a level of from 10 to 150 phr of the blend, morepreferably from 30 to 120 phr. Useful grades of carbon black asdescribed in RUBBER TECHNOLOGY 59-85 (1995) range from N110 to N990.More desirably, embodiments of the carbon black useful in for example,tire treads are N229, N351, N339, N220. N234 and N 110 provided in ASTM(D3037, D1510, and D3765). Embodiments of the carbon black useful in,for example, sidewails in tires, are N330, N351, N550, N650, N660, andN762. Embodiments of the carbon black useful in, for example,innerliners for tires are N550, N650, N660, N762, and N990.

The composition can include curative systems which are capable of curingthe functionalized elastomeric copolymer component to providevulcanizable compositions. Suitable curative systems can include organicperoxides, zinc oxide in combination with zinc stearate or stearic acidand, optionally, one or more of the following accelerators orvulcanizing agents: Permalux (di-ortho-tolylguanidine salt of dicatecholborate), HVA-2 (m-phenylene bis maleimide), Zisnet (2,4,6-trimercapto-5triazine), ZDEDC (zinc diethyl dithiocarbamate) and otherdithiocarbamates, Tetrone A (dipenta-methylene thiuram hexasulfide),Vultac-5 (alkylated phenol disulfide), SP1045 (phenol formaldehyderesin), SP1056 (brominated alkyl phenol formaldehyde resin), DPPD(diphenyl phenylene diamine), salicyclic acid (o-hydroxy benzoic acid),wood rosin (abietic acid), and TMTDS (tetramethyl thiuram disulfide) incombination with sulfur.

The compositions of the invention may also contain other conventionaladditives such as dyes, pigments antioxidants heat and lightstabilizers, plasticizers, oils and other ingredients as known in theart.

Blending of the fillers, additives, and/or curative components may becarried out by combining the desired components and the nanocomposite ofthe present invention in any suitable mixing device such as a BANBURYmixer, BRABENDER mixer or preferably a mixer/extruder and mixing attemperatures in the range of 120° C. up to 300° C. under conditions ofshear sufficient to allow the components to become uniformly dispersedwithin the polymer to form the nanocomposite.

The compositions can be extruded, compression molded, blow molded orinjection molded into various shaped articles including fibers, films,industrial parts such as automotive parts, appliance housings, consumerproducts, packaging and the like. The resulting articles can exhibitboth high impact strength and low vapor permeability. In particular, thecomposition described herein is useful for air barriers such asbladders, and automotive (including truck, commercial and/or passenger)or aircraft innerliners and inner tubes.

The invention, accordingly, provides the following embodiments:

-   -   A. A vulcanizable rubber composition, comprising an elastomer        comprising C₄ to C₇ isoolefin derived units, para-alkylstyrene        derived units, para-(haloalkylstyrene) derived units and        para-(triethylammoniumalkylstyrene) derived units having the        triethylammoniumalkyl group pendant to the elastomer E according        to formula (1) above wherein R and R¹ are the same or different        and are one of hydrogen, C₁ to C₇ alkyls, and primary and        secondary C₁ to C₇ alkyl halides; a filler; and a cure package;    -   B. The composition of embodiment A wherein the elastomer        comprises halogenated poly(isobutylene-co-p-methylstyrene)        wherein a portion of the benzylic halogen groups are        triethylamine-functionalized;    -   C. The composition of embodiment A or B wherein the elastomer        comprises a molar ratio of triethylamine functionality to        benzylic halogen from 1:100 to 1:1;    -   D. The composition of any preceding embodiment A-C wherein the        elastomer comprises a molar ratio of triethylamine functionality        to benzylic halogen from 1:20 to 1:2;    -   E. The composition of any preceding embodiment A-D wherein from        1 to 60 mole percent of the methylstyrene groups are halogenated        or triethylamine-functionalized;    -   F. The composition of any preceding embodiment A-E wherein the        elastomer comprises from 0.1 to 3 mole percent halomethylstyrene        and from 0.05 to 1 mole percent triethylammonimmethylstyrene; a        The composition of any preceding embodiment A-F wherein the        para-(triethylammoniumalkylstyrene) derived units are present at        from 0.01 to 0.5 percent by weight of the elastomer;    -   H. The composition of any preceding embodiment A-G wherein the        filler is selected from carbon black, modified carbon black,        silica, precipitated silica, clay, nano-clay and mixtures        thereof;    -   I. The composition of any preceding embodiment A-H wherein the        filler is an exfoliated nano-clay;    -   J. The composition of any preceding embodiment A-I wherein the        elastomer comprises a Mooney viscosity (ML 1+8, 125° C.) from 30        to 120;    -   K. An elastomer comprising C₄ to C₇ isoolefin derived units,        para-alkylstyrene derived units, para-(haloalkylstyrene) derived        units and para-(triethylammoniumalkylstyrene) derived units        having the triethylammoniumalkyl group pendant to the elastomer        E according to formula (I) above wherein R and R¹ are the same        or different and are one of hydrogen, C₁ to C₇ alkyls, and        primary and secondary C₁ to C₇ alkyl halides, the elastomer        having a Mooney viscosity (ML 1+8, 125° C.) from 30 to 120;    -   L. The elastomer of embodiment K wherein the elastomer comprises        halogenated poly(isobutylene-co-p-methylstyrene) wherein a        portion of the benzylic halogen groups are        triethylamine-functionalized;    -   M. The elastomer of embodiment K or L wherein the elastomer        comprises a molar ratio of triethylamine functionality to        benzylic halogen from 1:100 to 1:1;    -   N. The elastomer of any preceding embodiment K-M wherein the        elastomer comprises a molar ratio of triethylamine functionality        to benzylic halogen from 1:20 to 1:2;    -   O. The elastomer of any preceding embodiment K-N wherein from 1        to 60 mole percent of the methylstyrene groups are halogenated        or triethylamine-functionalized;    -   P. The elastomer of any preceding embodiment K-O wherein the        elastomer comprises from 0.1 to 3 mole percent halomethylstyrene        and from 0.05 to 1 mole percent triethylammoniummethylstyrene;    -   Q. The elastomer of any preceding embodiment K-P wherein the        para(triethylammoniumalkylstyrene) derived units are present at        from 0.01 to 0.5 percent by weight of the elastomer;    -   R. An article comprising the elastomer of any preceding        embodiment K-Q in an air impermeable layer of the article;    -   S. A tire innerliner comprising the vulcanizable rubber        composition according to any preceding embodiment A-J;    -   T. A method of preparing an elastomeric article, comprising: (1)        melt processing a mixture of partially ionomerized, partially        halogenated elastomer, filler and cure package; (2) forming the        melt processed mixture into a green article, and (3) curing the        formed article, wherein the elastomer comprises C₄ to C₇        isoolefin derived units, para-alkylstyrene derived units,        para-(haloalkylstyrene) derived units and        para-(trialkylammoniumalkylstyrene) derived units having the        triethylaminoalkyl group pendant to the elastomer E according to        formula (I) above wherein R and R¹ are the same or different and        are one of hydrogen, C₁ to C₇ alkyls, and primary and secondary        C₁ to C₇ alkyl halides and has a Mooney viscosity (ML 1+8, 125°        C.) from 30 to 120;    -   U. The method of embodiment T wherein the elastomer comprises        halogenated poly(isobutylene-co-p-methylstyrene) wherein a        portion of the benzylic halogen groups are        triethylamine-functionalized;    -   V. The method of embodiment T or U wherein the elastomer        comprises a molar ratio of triethylamine functionality to        benzylic halogen from 1:100 to 1:1:    -   W. The method of any preceding embodiment T-V wherein the        elastomer comprises a molar ratio of triethylamine functionality        to benzylic halogen from 1:20 to 1:2;    -   X. The method of any preceding embodiment T-W wherein from 1 to        60 mole percent of the methylstyrene groups are halogenated or        triethylamine-functionalized;    -   Y. The method of any preceding embodiment T-X wherein the        elastomer comprises from 0.5 to 20 weight percent methylstyrene;    -   Z. The method of any preceding embodiment T-Y wherein the        elastomer comprises from 0.1 to 3 mole percent halomethylstyrene        and from 0.05 to 1 mole percent triethylammoniummethylstyrene;    -   AA. The method of any preceding embodiment T-Z wherein the        elastomer further comprises multiolefin derived units,        halogenated multiolefin derived units, or a combination thereof;    -   BB. The method of any preceding embodiment T-AA wherein the        mixture in the melt processing further comprises a secondary        rubber selected from the group consisting of natural rubber,        polybutadiene rubber, nitrite rubber, silicon rubber,        polyisoprene rubber, poly(styrene-co-butadiene) rubber,        poly(isoprene-co-butadiene) rubber, styrene-isoprene-butadiene        rubber, ethylene-propylene rubber brominated butyl rubber,        chlorinated butyl rubber, halogenated isoprene, halogenated        isobutylene copolymers, polychloroprene, star-branched        polyisobutylene rubber, star-branched brominated butyl rubber,        poly(isobutylene-co-isoprene) rubber,        poly(isobutylene-co-p-methylstyrene), halogenated        poly(isobutylene-co-p-methylstyrene) and mixtures thereof;    -   CC. The method of any preceding embodiment T-BB wherein the        para-(triethylammoniumalkylstyrene) derived units are present at        from 0.01 to 0.5 percent by weight of the elastomer;    -   DD. The method of any preceding embodiment T-CC wherein the        filler is selected from carbon black, modified carbon black,        silica precipitated silica, clay, nanoclay and mixtures thereof;    -   EE. The method of any preceding embodiment T-DD wherein the        filler comprises nanoclays;    -   FF. The method of embodiment EE wherein the nanoclay is        exfoliated;    -   GG. The method of embodiment FF wherein the nanoclay is        exfoliated with an exfoliating agent selected from the group        consisting of ammonium ion, alkylamines, alkylammonium ion        (primary, secondary, tertiary and quaternary), phosphonium or        sulfonium derivatives of aliphatic, aromatic and arylaliphatic        amines, phosphines, sulfides and mixtures thereof;    -   HH. The method of any preceding embodiment EE-GG comprising from        1 to 100 phr of the nanoclays;    -   II. The method of any preceding embodiment T-HH wherein the        curing agents comprise zinc, zinc stearate, fatty acids, sulfur,        or a mixture thereof;    -   JJ. The method of any preceding embodiment T-II wherein the        article comprises an inner tube;    -   KK. The method of any preceding embodiment T-JJ wherein the        article comprises a tire wherein the green article comprises a        tire innerliner formed from the elastomer mixture;    -   LL. The method of any preceding embodiment T-KK comprising        adjusting an overall content of the        para-(triethylammoniumalkylstyrene) in the elastomer to control        a viscosity of the mixture in the melt processing.

EXAMPLES

The following non-limiting examples are illustrative of the presentinvention.

Example 1 Comparative—100-TEA-BIMS

Fifty grams of EXXPRO™ brominated isobutylene-para-methylstyrenecopolymer (BIMS) (MDX 03-1: 10 wt % para-methylstyrene (PMS), 0.85 mol %BrPMS, Mooney 31.5) were dissolved in 500 mL of toluene in a 1-Lreactor. Triethylamine (TEA) (4.38 g) was dissolved in 150 mL ofisopropyl alcohol and added to the reactor. The reaction mixture washeated to 85-86° C. and refluxed for 6 hours. The product wasprecipitated by adding 1000 mL of isopropyl alcohol to the polymercement. After drying in a vacuum oven at 80° C. for 16 hours, the ¹H NMRanalysis of the precipitate showed complete or substantially 100%conversion of benzylic bromide to ammonium functionality in theresulting functional polymer (100-TEA-BIMS).

Example 2 36-TEA-BIMS

One hundred grams of EXXPRO™ BIMS polymer (MDX 03-1: 10 wt % of PMS,0.85 mol % BrPMS, Mooney 31.5) were dissolved in 750 mL of toluene in a2-L reactor. TEA (1.46 g) was dissolved in 150 mL of isopropyl alcoholand added to the reactor. The reaction mixture was heated to 85-86° C.and refluxed for 6 hours. The product was precipitated by adding 1000 mLof isopropyl alcohol to the polymer cement. After drying in a vacuumoven at 80° C. for 16 hours, the ¹H NMR analysis of the precipitateshowed 36.5% conversion of benzylic bromide to ammonium in the resultingfunctional polymer (36-TEA-BIMS).

Example 3 21-TEA-BIMS

One hundred grams of EXXPRO™ BIMS polymer (MDX 03-1: 10 wt % of PMS,0.85 mol % BrPMS, Mooney 31,5) were dissolved in 750 mL of toluene in a2-L reactor. TEA (0.73 g) was dissolved in 150 mL of isopropyl alcoholand added to the reactor. The reaction mixture was heated to 85-86° C.and refluxed for 6 hours. The product was precipitated by adding 1000 mLof isopropyl alcohol to the polymer cement. After drying in a vacuumoven at 80° C. for 16 hours, the ¹ H NMR analysis of the precipitateshowed 21.2% conversion of benzylic bromide to ammonium in the resultingfunctional polymer (21-TEA-RIMS).

Example 4 9-TEA-BIMS

One hundred grams of EXXPRO™ BIMS polymer (MDX 03-1: 10 wt % of PMS,0.85 mol % BrPMS, Mooney 31.5) were dissolved in 750 mL of toluene in a2-L reactor. TEA (0.37 g) was dissolved in 150 mL of isopropyl alcoholand added to the reactor. The reaction mixture was heated to 85-86° C.and refluxed for 6 hours. The product was precipitated by adding 1000 mLof isopropyl alcohol to the polymer cement. After drying in a vacuumoven at 80° C. for 16 hours, the ¹H NMR analysis of the precipitateshowed 9.4% conversion of benzylic bromide to ammonium functionality inthe resulting functional polymer (9-TEA-RIMS).

Example 5 6-TEA-BIMS

One hundred grams of EXXPRO™ BIMS polymer (10 wt % PMS, 0.85 mol %BrPMS, Mooney 31.5) were dissolved in 750 mL of toluene in a 2-1reactor. Triethylamine (0.18 g) was dissolved in 150 mL of isopropylalcohol and added to the reactor. The reaction mixture was heated to85-86° C. and refluxed for 6 hours. The product was precipitated byadding 1000 mL of isopropyl alcohol to the polymer cement. After dryingin a vacuum oven at 80° C. for 16 hours, the ¹H NMR analysis of theprecipitate showed 5.9% conversion of benzylic bromide to ammonium inthe resulting functional polymer (6-TEA-BIMS).

Example 6 Mooney Viscosity Measurements

Mooney viscosity (ML 1+8, 125° C.) of the functional polymers inExamples 1 through 5 was measured according to ASTM 1646 Method. Theresults are tabulated in Table 1.

TABLE 1 Viscosity of TEA-BIMS Polymers BrPMS Mooney (ML PolymerConversion (%) 1 + 8, 125° C.) EXXPRO BIMS 0 31.5  6-TEA-BIMS 5.9 38.5 9-TEA-BIMS 9.4 49.9 21-TEA-BIMS 21.2 88.2 36-TEA-BIMS 36.5 111.8100-TEA-BIMS  100 ND ND = Not determined.

The tabulated results shown in FIG. 1 indicate a substantially linearrelationship between the degree of TEA functionalization (BrPMSconversion) and the Mooney viscosity, which can be used to obtain atarget effective molecular weight for compounding purposes. In contrast,FIG. 1 also shows that in BIMS functionalized with dimethyl ethanolamine, which has two smaller methyl groups replacing the ethyl groupsfrom TEA, the Mooney viscosity increases too rapidly with the level offunctionality, and the processability of the polymer is too difficult tocontrol.

Example 7 MOCON Permeability Measurement

Functional TEA-BIMS polymers were mixed with carbon black and curativesin the following proportions:

TABLE 2 Elastomer Formulations for Permeability DesignationMaterial/Source PHR TEA-BIMS Examples 2-5 100 N660 Carbon Black, CabotCorp. (Billerica, MA) 60 Stearic Acid C. K. Witco Corp. (Taft, LA) 1Kadox 911 ZnO, C. P. Hall (Chicago, IL) 1 MBTS 2-Mercaptobenzothiazoledisulfide, R. T. Vanderbilt 1 (Norwalk, CT) or Elastochem (Chardon, OH)

The TEA-BIMS polymer was loaded into a BRABENDER mixer at a temperatureof 130-145° C. and mixed with the carbon black (N660) for 7 minutes. Themixture was further mixed with the curatives package (stearic acid,Kadox 911, and MBTS) at 40° C. and 40 rpm for 3 minutes. The resultingrubber compounds were milled, compression molded and cured at 170° C.All specimens were compression molded with slow cooling to providedefect-free pads. A compression and curing, press was used for rubbersamples. Typical thickness of a compression molded pad was around 0.38mm (15 mil). Using an Arbor press, 5 cm (2-in.) diameter disks werepunched out from molded pads for permeability testing. These disks wereconditioned in a vacuum oven at 60° C. overnight prior to themeasurement. Disks were tested for oxygen permeation measurements wereperformed on using a MOCON OX-TRAM 2/61 permeability tester at 40° C.with nitrogen on one side of the disk at 0.07 MPa(g) (10 psig) and 0.07MPa(g) (10 psig) oxygen on the other. The time required for oxygen topermeate through the disk, or for oxygen concentration on the nitrogenside to reach a constant value, was recorded and used to determine theoxygen permeability. Where two samples were prepared using the sameprocedure, permeation rate results are given in Table 3 for each sample.

TABLE 3 Permeability of TEA-BIMS/Carbon Black Formulations ElastomerPermeation Rate Permeation Rate Formulation (mm · cc/m2 · day, 40° C.)(mm · cc/m2 · day, 40° C.) 36-TEA-BIMS 108.36 104.46 (Example 2)21-TEA-BIMS 107.63 110.64 (Example 3)  9-TEA-BIMS 107.80 106.08 (Example4)  6-TEA-BIMS 108.31 106.00 (Example 5)

These results show that the oxygen permeability of TEA-BIMS elastomersformulated with filler such as carbon black was low over the range ofTEA functionality tested, from 6 to 36% BrPMS conversion. The oxygenpermeability does not seem to be substantially dependent on the degreeof TEA functionality.

Example 8 19-TEA-BIMS in an Innerliner Formulation

One hundred fifty grams of EXXPRO™ BIMS polymer (10 wt % of PMS, 0.85mol % BrPMS, Mooney 31.5) were dissolved in 1200 mL of toluene in a 2-Lreactor. TEA (1.31 g) was dissolved in 200 mL of isopropyl alcohol andadded to the reactor. The reaction mixture was heated to 85-86° C. andrefluxed for 6 hours. The product was precipitated by adding 1000 mL ofisopropyl alcohol to the polymer cement. After drying in a vacuum ovenat 80° C. for 16 hours, the ¹H NMR analysis of the precipitate showed18.8% conversion of benzylic bromide to ammonium functionality in theresulting functional polymer (19-TEA-BIMS).

The 19-TEA-BIMS and unmodified BIMS elastomer were formulated withcarbon black and with and without an organoclay according to the recipein Table 4.

TABLE 4 Nanocomposite/Elastomer Formulations for Property EvaluationDesignation Material/Source PHR EXXPRO BIMS 10 wt % PMS, 0.85 mol %BrPMS, 100.0 Mooney 31.5; 19-TEA-BIMS Example 8 N772 Carbon Black, SidRichardson Carbon Co. or 51.0 another supplier CLOISITE 20AMontmorillonite modified with dimethyl- 7.8 dihydrogenated tallowammonium chloride, Southern Clay Products, Inc. Tackifier Phenolictackifier resin, SI Group, HRJ-2765 or 2.5 another supplier Stearic AcidC. K. Witco Corp. or another supplier 1.5 Curatives Sulfur, ZnO andAccelerator 4.2

The BIMS or TEA-BIMS polymer was loaded into a BANBURY mixer andpremasticated for 30 seconds with a rotor speed of 40 RPM at atemperature of 60° C. Next, the rotor speed was increased to 60 RPM andthe carbon black (N772) and organoclay (CLOISITE 20A) were added. At100° C. the tackifier resin and the stearic acid were added and mixingcontinued until the temperature reached 145° C. The mixture was placedonto a cool mill where the curatives were added. Samples forpermeability measurements were further calendered to a thickness of 1.0mm and then compression molded and cured at 150° C. The oxygentransmission rate (permeability) was measured on a MOCON 2/61 at 40° C.as described above, and samples evaluated for 10% and 100% modulus, andelongation at break. The results are given in Table 5.

Moduli of elongation were measured at 10% and 100% elongation at atemperature of 23° C. in accordance with ASTM D412 on ASTM C testpieces. These measurements are true secant moduli, that is to say thesecant moduli were calculated based on the actual cross-sectional areaof the test piece at the given elongation.

The elongation property was measured as elongation at break (%), whichis measured at 23° C. in accordance with ASTM D412 on ASTM C testpieces.

TABLE 5 Permeability and Properties of 19-TEA-BIMS/BIMS Formulationswith and without Nanoclay 19-TEA- 19-TEA- Component or BIMS BIMS BIMSNano- BIMS Nano- Property Elastomer Elastomer composite composite BIMS,phr 100 100 19-TEA-BIMS, phr 100 100 Organoclay, phr 7.8 7.8 Mooney (ML1 + 4, 82 84 45 77 100° C.) Modulus @ 10% 2.9 2.6 3.7 4.0 (23° C.), MPaModulus @ 100% 1.37 1.16 1.40 1.72 (23° C.), MPa Elongation at Break 558670 611 593 (23° C.), % Permeation Rate 125 108 105 79 (40° C.), mm ·cc/m2 · day Permeability — −13.6 −16.0 −36.8 change, %

As shown in Table 5, in an innerliner formulation the TEA functionalizedpolymer 19-TEA-BIMS yielded a 13.6% permeability improvement (reduction)in the formulation without organoclay compared to the unmodified BIMS.Additionally, when the 19-TEA-BIMS was used with CLOISITE 20Aorganoclay, the nanocomposite yielded a further permeability reduction.Surprisingly, both the uncured processability properties and the curedphysical properties were suitable for a tire innerliner.

The nanocomposites were also examined by x-ray diffraction at roomtemperature using a Scintag XDS-2000 theta-theta diffraction system,with a sealed Cu X-ray tube and a Germanium detector. The radiation wasCu Kalpha-1 (1.54056 angstroms) with Cu-K radiation generated at 40 mAand 50 kV. Diffraction spectra were obtained over a 20 range of 2° to10° in steps of 0.02° and a counting time of 3 seconds at each angularposition.

FIG. 2 compares the X-ray diffraction spectra of the BIMS/CLOISITE 20Ananocomposite with the nanocomposite with 19-TEA-BIMS. In general, areduction in the peak intensity indicates a more random or dispersedorientation of the clay particles. The 19-TEA-BIMS nanocomposite hadenhanced d-spacing, i.e. a larger spacing between clay sheets,indicating a higher degree of intercalation and/or exfoliation in theTEA-BIMS nanocomposite.

Similarly, FIGS. 3 and 4 are transmission electron microscopy (TEM)images of the 19-TEA-BIMS nanocomposite and the BIMS nanocomposite,respectively. The 19-TEA-BIMS nanocomposite TEM image (FIG. 3) shows ahigh degree of clay exfoliation, whereas the BIMS nanocomposite TEMimage (FIG. 4) shows large tactoids of unseparated clay sheets.

Embodiments of the final nanocomposite of the present invention areuseful as air barriers, such as used in producing innerliners for motorvehicles. In particular, the nanocomposites are useful in innerlinersand inner tubes for articles such as truck tires, bus tires, passengerautomobile, motorcycle tires, and the like.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to many differentvariations not illustrated herein. For these reasons, then, referenceshould be made solely to the appended claims for purposes of determiningthe true scope of the present invention.

All priority documents are herein fully incorporated by reference forall jurisdictions in which such incorporation is permitted. Further, alldocuments cited herein, including testing procedures, are herein fullyincorporated by reference for all jurisdictions in which suchincorporation is permitted.

1. A vulcanizable rubber composition, comprising: an elastomercomprising C₄ to C₇ isoolefin derived units, para-alkylstyrene derivedunits, para-(haloalkylstyrene) derived units andpara-(triethylammoniumalkylstyrene) derived units having thetriethylammoniumalkyl group pendant to the elastomer E according to thefollowing formula:

wherein R and R¹ are the same or different and are one of hydrogen, C₁to C₇ alkyls, and primary and secondary C₁ to C₇ alkyl halides; afiller; and a cure package.
 2. (canceled)
 3. The vulcanizable rubbercomposition of claim 1 wherein the elastomer comprises a molar ratio oftriethylamine functionality to benzylic halogen from 1:100 to 1:1. 4.(canceled)
 5. (canceled)
 6. (canceled)
 7. The vulcanizable rubbercomposition of claim 1, wherein the para-(triethylammoniumalkylstyrene)derived units are present at from 0.01 to 0.5 percent by weight of theelastomer.
 8. (canceled)
 9. The vulcanizable rubber composition of claim1, wherein the filler is an exfoliated nano-clay.
 10. The vulcanizablerubber composition of claim 1 wherein the elastomer comprises a Mooneyviscosity (ML 1+8, 125T) from 30 to
 120. 11. An elastomer comprising: C₄to C₇ isoolefin derived units, para-alkylstyrene derived units,para-(haloalkylstyrene) derived units andpara-(triethylammoniumalkylstyrene) derived units having thetriethylammoniumalkyl group pendant to the elastomer E according to thefollowing formula:

wherein R and R¹ are the same or different and are one of hydrogen, C₁to C₇ alkyls, and primary and secondary C₁ to C₇ alkyl halides, theelastomer having a Mooney viscosity (ML 1+8, 125° C.) from 30 to 120.12. (canceled)
 13. The elastomer of claim 11 wherein the elastomercomprises a molar ratio of triethylamine functionality to benzylichalogen from 1:100 to 1:1.
 14. The elastomer of claim 11 wherein theelastomer comprises a molar ratio of triethylamine functionality tobenzylic halogen from 1:20 to 1:2.
 15. (canceled)
 16. (canceled)
 17. Theelastomer of claim 11, wherein the para-(triethylammoniumalkylstyrene)derived units are present at from 0.01 to 0.5 percent by weight of theelastomer.
 18. An article comprising the elastomer of claim 11 in an airimpermeable layer of the article.
 19. A tire innerliner, the tireinnerliner comprising a vulcanizable rubber composition, the rubbercomposition comprising: an elastomer comprising C₄ to C₇ isoolefinderived units, para-alkylstyrene derived units, para-(haloalkylstyrene)derived units and para-(triethylammoniumalkylstyrene) derived unitshaving the triethylammoniumalkyl group pendant to the elastomer Eaccording to the following formula:

wherein R and R¹ are the same or different and are one of hydrogen, C₁to C₇ alkyls, and primary and secondary C₁ to C₇ alkyl halides; afiller; and a cure package.
 20. (canceled)
 21. The innerliner of claim19 wherein the elastomer comprises a molar ratio of triethylaminefunctionality to benzylic halogen from 1:100 to 1:1.
 22. (canceled) 23.The innerliner of claim 19, wherein the filler is an exfoliatednano-clay.
 24. (canceled)
 25. A method of preparing an elastomericarticle, comprising: melt processing a mixture of partially ionomerized,partially halogenated elastomer, filler and cure package; forming themelt processed mixture into a green article; and curing the formedarticle; wherein the elastomer comprises C₄ to C7 isoolefin derivedunits, para-alkylstyrene derived units, para-(haloalkylstyrene) derivedunits and para-(trialkylammoniumalkylstyrene) derived units having thetriethylaminoalkyl group pendant to the elastomer E according to thefollowing formula:

wherein R and R¹ are the same or different and are one of hydrogen, C₁to C₇ alkyls, and primary and secondary C₁ to C₇ alkyl halides and has aMooney viscosity (ML 1+8, 125° C.) from 30 to
 120. 26. (canceled) 27.The method of claim 25 wherein the elastomer comprises a molar ratio oftriethylamine functionality to benzylic halogen from 1:100 to 1:1. 28.(canceled)
 29. (canceled)
 30. (canceled)
 31. (canceled)
 32. (canceled)33. The method of claim 25, wherein the mixture in the melt processingfurther comprises a secondary rubber selected from the group consistingof natural rubber, polybutadiene rubber, nitrile rubber, silicon rubber,polyisoprene rubber, poly(styrene-co-butadiene) rubber,poly(isoprene-co-butadiene) rubber, styrene-isoprene-butadiene rubber,ethylene-propylene rubber, brominated butyl rubber, chlorinated butylrubber, halogenated isoprene, halogenated isobutylene copolymers,polychloroprene, star-branched polyisobutylene rubber, star-branchedbrominated butyl rubber, poly(isobutylene-co-isoprene) rubber,poly(isobutylene-co-p-methylstyrene), halogenatedpoly(isobutylene-co-p-methylstyrene) and mixtures thereof.
 34. Themethod of claim 25, wherein the para-(triethylammoniumalkylstyrene)derived units are present at from 0.01 to 0.5 percent by weight of theelastomer.
 35. (canceled)
 36. The method of claim 25, wherein the fillercomprises nanoclay.
 37. The method of claim 36, wherein the nanoclay isexfoliated.
 38. The method of claim 36, wherein the nanoclay isexfoliated with an exfoliating agent selected from the group consistingof ammonium ion, alkylamines, alkylammonium ion (primary, secondary,tertiary and quaternary), phosphonium or sulfonium derivatives ofaliphatic, aromatic and arylaliphatic amines, phosphines, sulfides andmixtures thereof.
 39. (canceled)
 40. (canceled)
 41. (canceled)
 42. Themethod of claim 25 wherein the article comprises a tire wherein thegreen article comprises a tire innerliner formed from the elastomermixture.
 43. (canceled)